Christoph Pilger

Large Meteoroids as Global Infrasound Reference Events

The explosive fragmentation of large meteoroids entering the Earth’s atmosphere is one of the strongest sources of infrasound and can be detected at distances of thousands of kilometers by arrays all over the world. Influence parameters on the detection capability are quantified for a single infrasound station and for the complete infrasound network of the International Monitoring System (IMS) operated by the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO). They are applied to a number of strong bolides of the past 15 years including the 2013 Chelyabinsk, 2010 Sulawesi, and 2009 North Pacific events. Long-range infrasound propagation modeling and realistic atmospheric background conditions are used to identify propagation paths that connect the sources and globally distributed receivers, highlighting usual as well as unusual propagation pattern, to stations detecting and stations not detecting a meteorite event. Potential influences on infrasound detection capability are due to the directivity of the acoustic source energy emission, the long-range ducting via stratosphere and thermosphere and the diurnal change of meteorological parameters and noise conditions at the stations during the signal arrivals. Since infrasound of large bolides has probably the most similar characteristics to an atmospheric nuclear explosion, it can be utilized as reference event for studies on the global performance of the CTBTO infrasound network. Detections and non-detections of bolide infrasound at the more than 40 operational IMS infrasound stations are studied for the estimation of station and network performance and thus verification of nuclear test ban.